The invention relates to a hydraulic cam follower for the simultaneous actuation of several identically actuated gas-exchange valves, especially for a cam follower for a tappet pushrod valve train of an internal combustion engine.
In the “single” action cam followers or roller tappets known from the state of the art, the pressure piston runs directly in a respective borehole of the housing of the cam follower with one end for supporting the tappet pushrod with its outer casing. Here, the outer casing and borehole are fine-machined through grinding for forming a hydraulic leakage gap. In practice, for cam follower diameters typical today, a high diameter accuracy of, for example, 5 μm at Rz 1.5 is required.
However, if in a preferably cylindrical housing of the cam follower, two pressure pistons lying one next to the other are applied in corresponding non-concentric guides, of which each communicates with one tappet pushrod, then fine machining of these guides through grinding has proven to be extremely complicated.